* BINARY_PLUS according to context. */
    MINUS = 2,			/* Ambiguous. Resolves to UNARY_MINUS or
				 * BINARY_MINUS according to context. */
    BAREWORD = 3,		/* Ambiguous. Resolves to BOOL_LIT or to
				 * FUNCTION or a parse error according to
				 * context and value. */
    INCOMPLETE = 4,		/* A parse error. Used only when the single
				 * "=" is encountered.  */
    INVALID = 5,		/* A parse error. Used when any punctuation
				 * appears that's not a supported operator. */
    COMMENT = 6,		/* Comment. Lasts to end of line or end of
				 * expression, whichever comes first. */

    /* Leaf lexemes */

    BINARY_MINUS = BINARY | MINUS,
    COMMA = BINARY | 3,		/* The "," operator is a low precedence binary
				 * operator that separates the arguments in a
				 * function call. The additional constraint
				 * that this operator can only legally appear
				 * at the right places within a function call
				 * argument list are hard coded within
				 * ParseExpr().  */
    MULT = BINARY | 4,
    DIVIDE = BINARY | 5,
    MOD = BINARY | 6,
    LESS = BINARY | 7,
    GREATER = BINARY | 8,
    BIT_AND = BINARY | 9,
    BIT_XOR = BINARY | 10,